Valve drive

ABSTRACT

The invention relates to a valve timing mechanism, in particular for four-cycle engines, having the following components:
         a rocker arm frame ( 2 ) which has two bars ( 34, 35 ) for accommodating rocker arms;   hydraulic elements ( 6 );   a steel sheet part which is arranged between the hydraulic elements ( 6 ) and the rocker arm frame ( 2 );   a pressurized oil line;   deep-drawn steel sheet rocker arms ( 1 ) which are configured uniformly, having a U-shaped cross section, a cylindrical roller, a cap ( 4 ) for a supporting ball ( 5 ) of the hydraulic element ( 6 ), and having contact elements for the valve stems of the inlet and outlet valves.       

     According to the invention, the manufacturing costs of the steel sheet rocker arms are reduced by the fact that the outer pistons ( 9 ) of the hydraulic elements ( 6 ) are guided in blind bores ( 8 ) of the rocker arm frame ( 2 ), and by the fact that a steel disk ( 11 ) is arranged at the bottom of the blind bores ( 8 ) as a stop for the inner piston ( 10 ).

This application is a 371 of PCT EP 2004/008066 filed Jul. 20, 2004.

FIELD OF THE INVENTION

The invention relates to a valve timing mechanism for four-cycleengines, having the following components:

-   -   a rocker arm frame (2) which is configured in one piece from        lightweight metal and has two bars (34, 35) which are connected        by webs (36, 37) for accomodating rocker arms;    -   hydraulic elements (6) for valve clearance compensation which        have an outer piston (9) which is open on one side and has a        supporting ball (5) which is configured in one piece at the        closed end of said outer piston (9), and an inner piston (10)        which is open on one side, is guided in the outer piston (9) and        is connected in flow terms via a spring-loaded ball valve (12)        to a high-pressure space (13) of said outer piston (9);    -   a steel sheet part which is arranged between the hydraulic        elements (6) and the rocker arm frame (2);    -   a pressurized oil line which is arranged in the longitudinal        extent of the rocker arm frame    -   (2) at the level of the open end of the hydraulic elements (6);    -   deep-drawn steel sheet rocker arms (1) which are configured        uniformly for all the valves, having a U-shaped cross section        and having cylindrical rollers (3) mounted on needle bearings        for at least one camshaft, and having a cap (4) for the        supporting ball (5), and having contact elements for the valve        stems of the inlet and outlet valves.

BACKGROUND OF THE INVENTION

In four-cycle engines having four valves, it is customary to use rockerarms to actuate the valves, which rocker arms are mounted on a commonrocker arm shaft. Different rocker arms are thereby required on accountof the different position of the valves.

In addition, hydraulic clearance compensation elements which arearranged at the valve-side end of the rocker arms increase its polarmoment of inertia. As a result, strengthened valve springs are therebyrequired which result in a stiffening and possible hardening of therocker arm shaft.

Moreover, the hydraulic clearance compensation elements which areinstalled in the rocker arm require a complex pressurized oil supplymeans having fully machined pressurized oil lines. All the abovemeasures cause great manufacturing expenditure.

The PCT application WO 00/20730 describes a valve timing mechanism forfour-cycle engines which is improved compared with the above-describedprior art and has the following components:

-   -   a rocker arm frame which is configured in one piece from        lightweight metal and has two bars which are connected by webs,        for accommodating the rocker arms;    -   hydraulic elements for valve clearance compensation which have        an outer piston which is open on one side and has a supporting        ball which is configured in one piece at the closed end of said        outer piston, and an inner piston which is open on one side, is        guided in the outer piston and is connected in flow terms via a        spring-loaded ball valve to a high-pressure space of said outer        piston;    -   a steel sheet part which is arranged between the hydraulic        element and the rocker arm frame.;    -   a pressurized oil line which is arranged in the longitudinal        extent of the rocker arm frame at the level of the open end of        the hydraulic elements;    -   deep-drawn steel sheet rocker arms which are configured        uniformly for all the valves, having a U-shaped cross section        and having cylindrical rollers mounted on needle bearings for at        least one camshaft, and having a cap for the supporting ball,        and having contact elements for the valve stems of the inlet and        outlet valves.

Despite the improvements which are achieved by the above components,numerous requirements with regard to low manufacturing and assemblycosts are still not met.

OBJECT OF THE INVENTION

The invention is therefore based on the object of providing a valvetiming mechanism for four-cycle engines having preferably four valvesper cylinder, which valve timing mechanism is distinguished byinexpensive manufacturing and assembly.

SUMMARY OF THE INVENTION

According to the invention, the object is achieved by a valve timingmechanism, for four cycle engines, having the following components:

-   -   a rocker arm frame (2) which is configured in one piece from        lightweight metal and has two bars (34, 35) which are connected        by webs (36, 37) for accomodating rocker arms;    -   hydraulic elements (6) for valve clearance compensation which        have an outer piston (9) which is open on one side and has a        supporting ball (5) which is configured in one piece at the        closed end of said outer piston (9), and an inner piston (10)        which is open on one side, is guided in the outer piston (9) and        is connected in flow terms via a spring-loaded ball valve (12)        to a high-pressure space (13) of sald outer piston (9);    -   a steel sheet part which is arranged between the hydraulic        elements (6) and the rocker arm frame (2);    -   a pressurized oil line which is arranged in the longitudinal        extent of the rocker arm frame (2) at the level of the open end        of the hydraulic elements (6);    -   deep-drawn steel sheet rocker arms (1) which are configured        uniformly for all the valves, having a U-shaped cross section        and having cylindrical rollers (3) mounted on needle bearings        for at least one camshaft, and having a cap (4) for the        supporting ball (5), and having contact elements for the valve        stems of the inlet and outlet valves, wherein the outer pistons        (9) of the hydraulic elements (6) are guided in blind bores (8)        of the rocker arm frame (2), and in that a steel disk (11) is        arranged at the bottom of the blind bores (8) as a stop for the        inner piston (10).

An optimum pair of sliding elements is attained and the steel guidebushes used in the prior art can be omitted in a cost-saving manner as aresult of the fact that the outer pistons of the hydraulic elements areguided directly in blind bores of the lightweight metal rocker armframe.

The steel disk which is arranged at the bottom of the blind bore serves,inter alia, as a stop for the inner piston of the hydraulic element andthus prevents the wear which is possible there of the rocker arm frame.

It is advantageous that the diameter of the steel disks preferablycorresponds to that of the blind bores, and that the pressurized oilline is configured as a pressurized oil bore, the center line of whichis preferably tangent on the circumference of the center plane of thesteel disks of the hydraulic elements which are arranged in an offsetmanner.

In modern diesel engines, the valves are arranged in a twisted mannerabout the cylinder axis. As a result, the swirl channels can bepositioned more satisfactorily. This valve position results in an offsetof the respectively adjacent steel sheet rocker arms and their hydraulicelements. As a result of the position according to the invention of thepressurized oil bore, the steel disks of the offset hydraulic elementshave pressurized oil applied uniformly to their sides which are close tothe bottom and remote from the bottom, and their functioning is thusensured. However, applications are also conceivable, in which a higheror a lower position of the pressurized oil bore is advantageous.

Preferably radially arranged, matching channels which connect thepressurized oil bore to venting bores and to inner spaces of the innerpistons serve on the upper side and lower side of the steel disks forthe functional reliability of the hydraulic elements.

The air in the pressurized oil which collects in the upper region of thepressurized oil bore is discharged to the venting bores which arepreferably arranged in the center line of the hydraulic elements in therocker arm frame with a low oil leakage flow through the channels whichare arranged on the upper side of the disks. The pressurized oil fromthe lower region of the pressurized oil bores which is low in air passesvia the channels of the lower side of the steel disks into the innerspace of the inner pistons, from where it flows into a high-pressurespace of the outer piston via a spring-loaded ball valve duringcompensation of the valve clearance.

It is advantageous that the outer side of the inner pistons has a firstcircumferential groove in the overlap region with the inner side of theouter pistons, said first circumferential groove being connected to theinner space of the inner pistons via a radial bore. In this way, theleakage oil which is low in air from the high-pressure space of theouter pistons is collected in the circumferential groove of the innerpistons and is returned via the radial bore into the inner space of theinner pistons.

It is also advantageous that, on the outer circumference of the outerpistons in the region of their open end, a second circumferential grooveis arranged with a circlip which latches into a third circumferentialgroove in the end region of the blind bores. As a result, that outerpiston of the hydraulic elements which is connected to the steel sheetrocker arm is latched to the rocker arm frame. In this way, the rockerarm frame with all the rocker arms which are fastened to it is apreassembled unit which can be handled easily.

It is necessary for the adjusting function of the hydraulic elementsthat the length of the third circumferential groove corresponds at leastto the adjustment path of the hydraulic elements.

It has proven advantageous that the cross section of the deep-drawnsteel sheet rocker arm is configured as a U-profile which is open at thetop and has a profile bottom into which the cap is embossed, and that acylindrical shaped-out molding having a minimum transverse camber isprovided as a contact element for the valve stems at the valve-side endof the steel sheet rocker arms on the outer side of the profile bottom,the center line of said cylindrical shaped-out molding lying parallel tothe tilting axis of the steel sheet rocker arm.

Most of the hydraulic element is located in the upwardly open U-profileof the steel sheet rocker arm. In addition to the cap, the cylindricalshaped moldings having the minimum transverse camber and the guide railsare formed in the profile bottom without additional outlay onmanufacturing and installation space. The result is a considerablesaving in overall height and design costs in comparison with theU-profile which is specified in the prior art and is closed at the top.Moreover, a low polar moment of inertia of the steel sheet rocker armabout its tilting axis is achieved, and simple lateral guidance of saidsteel sheet rocker arm by the guide rails which are guided on the valvestems is attained.

One alternative to the guide rails consists in extended side walls whichare bent downward and backward and are welded to the profile bottom.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the invention result from the following descriptionand the drawings, in which an exemplary embodiment of the invention isshown diagrammatically and in which:

FIG. 1 shows a partial cross section A-A from FIG. 2 through a steelsheet rocker arm according to the invention which is fastened to arocker arm frame;

FIG. 2 shows a plan view of a part of the rocker arm frame from FIG. 1with the steel sheet rocker arm coupled to it;

FIG. 3 shows a front view of the rocker arm frame with coupled steelsheet rocker arms; and

FIG. 4 shows a partial view of the lower side of the rocker arm framewith coupled steel sheet rocker arms.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a longitudinal section A-A (cf. FIG. 2) through a steelsheet rocker arm 1 which is coupled to a rocker arm frame 2.

The steel sheet rocker arm 1 is configured as a two-armed lever. It isdriven by a camshaft (not shown), via a cylindrical roller 3 which ismounted on needle bearings, is supported on the rocker arm frame 2 via acap 4 and a supporting ball 5 of a hydraulic element 6 and acts on thevalve stems (likewise not shown) via a cylindrical shaped-out molding 7having a minimum transverse camber.

The hydraulic elements 6 serve for valve clearance compensation. Theyare guided in blind bores 8 in the lightweight metal of the rocker armframe 2.

The hydraulic elements 6 have a hollow-cylindrical outer piston 9 whichis open on one side, is made from steel and the closed end of which isformed in one piece with the supporting ball 5. A steel inner piston 10is guided with sealing play in the interior of the outer piston 9, theopen end of said steel inner piston 10 being supported on a steel disk11 on the bottom of the blind bore 8, and the closed end of said steelinner piston 10 being connected in flow terms to a high-pressure space13 of the outer piston 9 via a spring-loaded ball valve 12 which isarranged there.

The hydraulic elements 6 are supplied with pressurized oil via apressurized oil bore 14 which extends in the longitudinal direction ofthe rocker arm frame 2 and the center line of which is tangent on thecircumference of the center plane of the steel disks 11. The side 15 ofthe steel disks 11 which is close to the bottom and the side 16 of thesteel disks 11 which is remote from the bottom are supplied withpressurized oil on account of this position of the pressurized oil bore14.

Fine radial channels 29 (not shown) are arranged on both sides 15, 16 ofthe steel disks 11. The channels 29 of the side 15 which is close to thebottom guide pressurized oil which contains air and has collected in theupper region of the pressurized oil bores 14 to a venting bore 17 whichis arranged in the center line of the blind bore 8, starts from thebottom of the latter and opens into the valve timing mechanism space.

The channels 29 on that side 16 of the steel disk 11 which is remotefrom the bottom serve to supply an inner space 18 of the inner piston 10with pressurized oil which is largely free of air from the lower regionof the pressurized oil bore 14. In the case of closed inlet and outletvalves during the valve clearance compensation by the force of acompression spring 19 which is arranged in the high-pressure space 13,the outer piston 9 sucks pressurized oil out of the inner space 18 viathe ball valve 12 into the high-pressure space 13. This pressurized oilis highly pressurized as a result of the actuating forces during valveopening and flows into the sealing gap between outer and inner pistons9, 10. From there, this oil which is low in air passes via a firstcircumferential groove 20 of the inner piston 10 which is arranged inthe overlap region of the two pistons 10, 11 through a radial bore 21situated in this groove back into the inner space 18, from where it issucked into the high-pressure space 13 again.

The outer piston 9 has a second circumferential groove 22 on the outercircumference in the region of the open end, in which secondcircumferential groove 22 a circlip 23 is situated. The latter latchesinto a third groove 24 which is machined into the blind bore 8 in theregion of that end of the latter which is close to the bottom. Thisproduces a partially form-fitting and partially force-transmittingconnection between the rocker arm frame 2 and the hydraulic element 6,which connection prevents the hydraulic element 6 from falling out ofsaid rocker arm frame 2 and, as a result, makes simple assembly of thevalve timing mechanism possible.

The level of the third groove 24 corresponds to the maximum adjustmentpath of the hydraulic element 6. At the same time, it serves todistribute the pressurized oil over the circumference of the hydraulicelements 6 and the steel disks 11.

The steel sheet rocker arm 1 is configured as a deep-drawn U-profilewhich is open at the top and has a profile bottom 25. The cap 4 for thesupporting ball 5 is embossed into the profile bottom 25 and is part ofthe latter.

The inner side of the cap 4 is designed as what is known as a gothicprofile which has a plurality of radii which merge into one another andoffers a maximum contact surface area for the supporting ball 5.

The contact with the valve stems is ensured by a cylindrical shaped-outmolding 27 having low transverse camber of the outer side 26 of theprofile bottom 25 at the valve-side end of the steel sheet rocker arm 1.Here, the center line of the cylindrical shaped-out molding 27 isarranged parallel to the tilting axis of the steel sheet rocker arm 1.In conjunction with the cylindrical rollers which run on the camshaftand the caps 4 which adjust around the supporting balls 5 freely, thelow transverse camber of the cylindrical shaped-out moldings 27 allows amovement of the steel sheet rocker arm 1 about its longitudinal axis,which movement compensates for all positional tolerances of the valvetiming mechanism.

Two parallel guide rails 28 are formed in one piece with a rectangularcross section and at the distance of the diameter of the valve stems andin the tilting direction of the steel sheet rocker arms 1 on the outerside 26 of the profile bottom 25 in the region of the cylindricalshaped-out moldings 27 in a manner which follows their contour. As aresult, simple and effective lateral guidance of the steel sheet rockerarms 1 is ensured via the valve stems.

The hydraulic elements 6 which are latched in the rocker arm frame 2 areconnected captively to the steel sheet rocker arm 1 by holding clips 30which latch both into openings 31, 32 in the profile bottom 25 and intoa fourth circumferential groove 33 at the transition from the supportingball 5 to the outer piston 9. This results in a unit comprising rockerarm frame 2 and steel sheet rocker arms 1 which is easy to mount.

As is evident from all the figures, the steel sheet rocker arms 1 arearranged offset in accordance with the position of the valves but are ofidentical design. Compared with the rollers 3, the camshafts (not shown)are positioned at half the lateral offset of the steel sheet rocker arms1.

FIG. 2 shows a plan view of a part of the rocker arm frame 2 withcoupled steel sheet rocker arms 1 and an indication of the position ofthe sectional plane A-A. The first and second bars 34, 35 are connectedin one piece by a first web 36. The screw positions 27 of the screws forfastening the rocker arm frame 2 on the cylinder head and the ventingbores 17 are also shown. The longitudinal and lateral offset of thesteel sheet rocker arms 1 can be seen clearly.

FIG. 3 shows a front view of the rocker arm frame 2 with coupled steelsheet rocker arms 1. In addition to the view of the first and secondbars 34, 35 and the first web 36 which connects them, the closedpressurized oil bores 14 can be seen.

FIG. 4 shows a partial view of the lower side of the rocker arm frame 2with coupled steel sheet rocker arms 1. In addition to the first andsecond bars 34, 35, the first and second webs 36, 37 and the screwpositions 27 of the screws required for screwing to the cylinder headare shown.

The bottom view of the steel sheet rocker arm 1 shows the cylindricalroller 3 and the outer view of the cap 4 which, just like thecylindrical shaped-out molding 7 and the guide rails 28, will be formedby plastic deformation of the profile bottom 25.

The holding clips 30 are latched into the openings 31, 32, which holdingclips 30 serve on the upper side of the steel sheet rocker arm 1 toconnect it to the hydraulic element 6 which in turn is connected to therocker arm frame 2 by the circlip 23.

The solution according to the invention is distinguished by thefollowing advantages:

-   -   a pressure-resistant and thus functionally appropriate hydraulic        element 6 by means of venting the pressurized oil before it        flows into the inner space 18 of the inner piston 10 and        returning the high-pressure leakage oil flow which is low in air        to the inner piston 10;    -   the hydraulic elements 6 are connected captively to the rocker        arm frame 2 by circlips 23 and to the steel sheet rocker arms 1        by holding clips 30, the result of which is simple assembly of        the precompleted rocker arm frame 2;    -   low manufacturing costs, high strength with low weight and a low        rotational moment of inertia are achieved by chipless        manufacturing of the steel sheet rocker arms 1 in one piece;    -   most of the hydraulic element 6 is located in the upwardly open        U-profile of the steel sheet rocker arm 1. In addition to the        cap 4, the spherical or cylindrical shaped moldings 7 including        the guide rails 28 are formed in the profile bottom 25 without        additional outlay on manufacturing and installation space. The        result is a considerable saving in overall height and design        costs in comparison with a U-profile which is closed at the top.        Moreover, a low polar moment of inertia of the steel sheet        rocker arm 1 about its tilting axis is achieved, and simple        lateral guidance of said steel sheet rocker arm 1 by the valve        stems is attained.

LIST OF DESIGNATIONS

-   1 Steel sheet rocker arm-   2 Rocker arm frame-   3 Roller-   4 Cap-   5 Supporting ball-   6 Hydraulic element-   7 Cylindrical shaped-out molding-   8 Blind bore-   9 Outer piston-   10 Inner piston-   11 Steel disk-   12 Spring-loaded ball valve-   13 High-pressure space-   14 Pressurized oil bore-   15 Side of the steel disk which is close to the bottom-   16 Side of the steel disk which is remote from the bottom-   17 Venting bore-   18 Inner space-   19 Compression spring-   20 First circumferential groove-   21 Radial bore-   22 Second circumferential groove-   23 Circlip-   24 Third circumferential groove-   25 Profile bottom-   26 Outer side-   27 Screw position-   28 Guide rail-   29 Channel-   30 Holding clip-   31 First opening-   32 Second opening-   33 Fourth circumferential groove-   34 First bar-   35 Second bar-   36 First web-   37 Second web-   38 Inner side

1. A valve timing mechanism, for four-cycle engines, having thefollowing components: a rocker frame which is configured in one piecefrom lightweight metal and has at least one bar which is connected bywebs, for accomodating rocker arms; hydraulic elements for valveclearance compensation which have an outer piston which is open on oneside and has a supporting ball which is configured in one piece at theclosed end of said outer piston, and an inner piston which is open onone side, is guided in the outer piston and is connected in flow termsvia a spring-loaded ball valve to a high-pressure space of said outerpiston; a steel sheet part which is arranged between the hydraulicelements and the rocker arm frame; a pressurized oil line which isarranged in the longitudinal extent of the rocker arm frame at the levelof the open end of the hydraulic elements; deep-drawn steel sheet rockerarms which are configured uniformly for all the valves, having aU-shaped cross section and having cylindrical rollers mounted on needlebearings for at least one camshaft, and having a cap for the supportingball, and having contact elements for the valve stems of the inlet andoutlet valves, wherein the outer pistons of the hydraulic elements areguided in blind bores of the rocker arm frame, and in that the steelpart is designed as a steel disk arranged at the bottom of the blindbores as a stop for the inner piston and outer pistons are guideddirectly in blind bores of the light weight frame.
 2. A valve timingmechanism, for four-cycle engines, having the following components: arocker frame which is configured in one piece from lightweight metal andhas at least one bar which is connected by webs, for accomodating rockerarms; hydraulic elements for valve clearance compensation which have anouter piston which is open on one side and has a supporting ball whichis configured in one piece at the closed end of said outer piston, andan inner piston which is open on one side, is guided in the outer pistonand is connected in flow terms via a spring-loaded ball valve to ahigh-pressure space of said outer piston; a steel sheet part which isarranged between the hydraulic elements and the rocker arm frame; apressurized oil line which is arranged in the longitudinal extent of therocker arm frame at the level of the open end of the hydraulic elements;deep-drawn steel sheet rocker arms which are configured uniformly forall the valves, having a U-shaped cross section and having cylindricalrollers mounted on needle bearings for at least one camshaft, and havinga cap for the supporting-ball, and having contact elements for the valvestems of the inlet and outlet valves, wherein the outer pistons of thehydraulic elements are guided in blind bores of the rocker arm frame,and in that the steel part is designed as a steel disk arranged at thebottom of the blind bores as a stop for the inner piston and outerpistons are guided directly in blind bores of the light weight frame,the diameter of the steel disks corresponds to that of the blind bores,and in that the pressurized oil line is configured as a pressurized oilbore, the center line of which is preferably tangent on thecircumference of the center plane of the steel disks of the hydraulicelements which are arranged in an offset manner.
 3. A valve timingmechanism, for four-cycle engines, having the following components: arocker frame which is configured in one piece from lightweight metal andhas at least one bar which is connected by webs, for accomodating rockerarms; hydraulic elements for valve clearance compensation which have anouter piston which is open on one side and has a supporting ball whichis configured in one piece at the closed end of said outer piston, andan inner piston which is open on one side, is guided in the outer pistonand is connected in flow terms via a spring-loaded ball valve to ahigh-pressure space of said outer piston; a steel sheet part which isarranged between the hydraulic elements and the rocker arm frame; apressurized oil line which is arranged in the longitudinal extent of therocker arm frame at the level of the open end of the hydraulic elements;deep-drawn steel sheet rocker arms which are configured uniformly forall the valves, having a U-shaped cross section and having cylindricalrollers mounted on needle bearings for at least one camshaft, and havinga cap for the supporting-ball, and having contact elements for the valvestems of the inlet and outlet valves, wherein the outer pistons of thehydraulic elements are guided in blind bores of the rocker arm frame,and in that the steel part is designed as a steel disk arranged at thebottom of the blind bores as a stop for the inner piston and outerpistons are guided directly in blind bores of the light weight frame, onthose sides of the steel disks of the steel disks which are close to andremote from the bottom, matching, preferably radial channels arearranged which serve to connect the pressurized oil bore to ventingbores and to the inner space of the inner pistons.
 4. The valve timingmechanism of claim 3, wherein the venting bores in the rocker arm frameare arranged in the center line of the hydraulic elements.
 5. The valvetiming mechanism of claim 4, wherein the outer side of the inner pistonshas a first circumferential groove in the overlap region with the innerside of the outer psitons, said first circumferential groove beingconnected to the inner space of the inner pistons via a radial bore. 6.The valve timing mechanism of claim 5, wherein the outer circumferenceof the outer pistons in the region of their open end, a secondcircumferential groove is arranged with a circlip which latches into athird circumferential groove in the end region of the blind bores. 7.The valve timing mechanism of claim 6, wherein the length of the thirdcircumferential groove corresponds at least to the adjustment path ofthe hydraulic elements.
 8. The valve timing mechanism of claim 7,wherein the cross section of the deep-drawn steel sheet rocker arm isconfigured as a U-profile which is open at the top and has a profilebottom into which the cap is embossed.
 9. The valve timing mechanism ofclaim 8, wherein a cylindrical shaped-out molding having a minimumtransverse camber is provided as a contact element for the valve stemsat the valve-side end of the steel sheet rocker arms on the outer sideof the profile bottom, the center line of said cylindrical shaped-outmolding, lying parallel to the tilting axis of the steel sheet rockerarm.
 10. The valve timing mechanism of claim 9, wherein two parallelguide rails are formed in one piece with a rectangular cross section andat the distance of the diameter of the valve stems and in the tiltingdirection of the steel sheet rocker arms on the outer side of theprofile bottom in the region of the cylindrical shaped-out molding in amanner which follows its contour lying parallel to the tilting axis ofthe steel sheet rocker arm.